The present disclosure relates generally to an emissions abatement system including a fuel reformer, and more particularly to an emissions abatement system for regenerating SOX absorbed by a NOX trap.
Fuel reformers reform hydrocarbon fuel into a reformate gas such as hydrogen-rich gas. In the case of an onboard fuel reformer or a fuel reformer associated with a stationary power generator, the reformate gas produced by the fuel reformer may be utilized as fuel or fuel additive in the operation of an internal combustion engine. The reformate gas may also be utilized to regenerate or otherwise condition an emission abatement device associated with an internal combustion engine or as a fuel for a fuel cell.
According to an illustrative embodiment, a method of operating a fuel reformer to regenerate a NOX trap is provided. The method includes operating the fuel reformer to produce a reformate gas comprising hydrogen and carbon monoxide and advancing the reformate gas through the NOX trap to regenerate the NOX trap. The method also includes determining if a SOX regeneration of the NOX trap is to be performed and generating a SOX-regeneration control signal in response thereto. Further, the method includes raising the temperature of the NOX trap in response to the SOX-regeneration control signal and operating the fuel reformer so as to advance the reformate gas into the NOX trap in response to the SOX-regeneration control signal.
The step of raising the temperature of the NOX trap includes raising the temperature of exhaust gases advancing through the NOX trap from an internal combustion engine. The temperature of the exhaust gases may be raised, for example, by decreasing an air-to-fuel ratio of an air/fuel mixture being introduced into the internal combustion engine. The temperature of the exhaust gases may be raised to less than about 650xc2x0 C.
In one embodiment, the determining step includes determining the number of NOX purges performed and comparing the number of NOX purges performed to a predetermined set point number of NOX purges. The SOX-regeneration control signal is then generated when the number of NOX purges is greater than or equal to the predetermined set point number of NOX purges.
In another embodiment, the determining step includes determining if a predetermined period of time has elapsed since the NOX trap was last desulfated and generating a time-lapsed control signal in response thereto. Operating the fuel reformer in response to the SOX-regeneration signal further includes advancing the reformate gas into the NOX trap in response to generation of the time-lapsed control signal.
In still another embodiment, the determining step includes sensing the amount of SOX within the NOX trap. Further, the sensing step includes generating a trap-saturated control signal when the amount of SOX within the NOX trap reaches a predetermined accumulation level. As such, operating the fuel reformer in response to the SOX-regeneration signal further includes advancing the reformate gas into the NOX trap in response to generation of the trap-saturated control signal.
According to another illustrative embodiment, there is provided a fuel reformer assembly for producing a reformate gas. The fuel reformer assembly includes a fuel reformer and a reformer controller electrically coupled to the fuel reformer. The reformer controller includes a processing unit and a memory unit electrically coupled to the processing unit. The memory unit has stored therein a plurality of instructions which, when executed by the processing unit, causes the processing unit to (i) operate the fuel reformer so as to produce a reformate gas comprising hydrogen and carbon monoxide, (ii) operate the fuel reformer so as to advance the reformate gas through a NOX trap so as to regenerate the NOX trap, (iii) determine if a SOX regeneration of the NOX trap is to be performed and generate a SOX-regeneration control signal in response thereto, (iv) raise the temperature of the NOX trap in response to the SOX-regeneration control signal, and (v) operate the fuel reformer so as to advance the reformate gas into the NOX trap in response to the SOX-regeneration control signal. The raising the temperature step comprises generating a temperature control signal which is communicated to an engine control unit so as to cause the engine control unit to decrease an air-to-fuel ratio of an air/fuel mixture being introduced into an internal combustion engine. The decreased air-to-fuel ratio of the air/fuel mixture raises the temperature of exhaust gases exiting the internal combustion engine for advancement through the NOX trap.
According to still another illustrative embodiment, there is provided a method of desulfating a NOX trap including operating a fuel reformer so as to produce a reformate gas comprising hydrogen and carbon monoxide, and advancing the reformate gas into the NOX trap to react the hydrogen and carbon monoxide with SOX trapped on the NOX trap to remove SOX from the NOX trap.
The above and other features of the present disclosure will become apparent from the following description and the attached drawings.